Tuesday, January 31, 2012

A new review has provided more evidence of the importance of including a range of different fibre sources in a healthy diet, including grain foods. The meta-analysis of cohort studies reports that fibre from grain foods and particularly wholegrains is associated with reduced risk of bowel cancer, but fibre from fruit and vegetables does not have a significant association. Grain foods may be one key to help unlock the puzzle of our rising rates of bowel cancer.

Bowel cancer. It’s not really dinner time conversation, but maybe it should be. Colorectal cancer is one of the most common forms of cancer in Australia, affecting 1 in 12 people under the age of 85 and leading to the death of almost 80 people every week.

The good news is that if it is found early there is a high chance of survival, and even better news is that making smart choices about what you eat today could help reduce your chances of developing bowel cancer later.

Previous research has shown that people who eat higher-fibre foods, like fruit, vegetables and wholegrains, are less likely to develop a range of diseases, including bowel cancer. Recently, a systematic review and dose-response meta-analysis of 25 prospective cohort studies went one step further to determine if some high-fibre foods were better choices than others when it comes to preventing bowel cancer.

From an analysis of the eight cohort studies that reported on cereal fibre intake, the review found that for every 10g of cereal fibre, the risk of developing bowel cancer was reduced by 10% (RR=0.90 CI 0.83 – 0.97). The study also considered the effect of wholegrain foods including wholemeal bread, oats, wholegrain breakfast cereal, wholegrain rye bread, and brown rice. People who ate 3 serves of wholegrain foods per day were 17% less likely to develop bowel cancer than those people who didn’t eat wholegrain foods. Interestingly, the study found that fruit and vegetable fibre did not significantly help protect against bowel cancer (RR= 0.93, CI 0.82-1.05 and RR=0.98, CI 0.91-1.06 respectively).

The way in which fibre helps reduce the risk of colorectal cancer is due to several effects in the gut, but the precise mechanism is not yet fully understood. We know that fibre helps keep you regular which has many health benefits, but more recent research has also linked fibre in some grain foods to higher levels of bacteria in the bowel that produce short-chain-fatty-acids including butyrate. Recent research by the CSIRO found that increasing the intake of rye bread lead to significantly high levels of butyrate which is believed to help prevent cancer cell proliferation in the bowel.

According to the World Cancer Research Fund scientific review in 2011, other foods that may help fight bowel cancer are garlic, milk, and calcium. Other ways to reduce your chances of getting bowel cancer is to get at least 30 minutes of exercise every day, and to limit the amount of processed meat (like salami) in your diet.

Go Grains is concerned that the reduction in the serve size of grain foods in the revised Dietary Guidelines will send the wrong message to Australians – to limit core grain foods in the diet. We are recommending that the serve sizes remain the same and that the NHMRC considers a target number of wholegrain foods each day. Rather than suggesting people reduce core grain foods, Go Grains believes it is more important to encourage people to limit grain foods that are high in saturated fat and sodium and swap back to core grain foods.

A revision to the current Australian Dietary Guidelines is currently available in draft form for public comment (until February 29th). While most Australians are not aware of the Dietary Guidelines they are an important guide used by health professionals, policy makers, educators, food manufacturers, food retailers and researchers, to help improve the diets of Australians. So it is important that they send effective, evidence-based messages.

While Go Grains supports the revision to the Dietary Guidelines and acknowledges the huge amount of work that has gone into their development, we do have concerns about several of the key messages on grain and legume foods.

A reduction in serve size of grain foods

One of our key concerns is the change in serve size of grain foods from the recommendation in the 1998 Australian Guide to Healthy Eating, in most cases halving the serve size. For example a recommended serve of muesli is ¼ cup (30g) rather than ½ cup.

Go Grains is concerned that reducing the recommended serve size for grain foods will suggest Australians should reduce their core grain food consumption when our Consumption Study in 2011 indicates that Australians are already reducing their intake of core grain foods (1 slice of bread less per day than in 2009). Sending a message to reduce core grain foods is counter to the five evidence statements in the Guidelines that outline the benefits of core grain foods including reducing risk of heart disease, type 2 diabetes and colorectal cancer.

Also, if food manufacturers change their recommended serve sizes to align with the new recommendation, many products will no longer be labelled high in fibre and the ability to communicate the benefits of high fibre foods will be lost.

We recognise the need to encourage a major shift in the form in which people consume cereal foods towards core forms such as breads, rice, pasta, breakfast cereals and away from pastries, cakes and biscuits. To support this, we believe the Dietary Guidelines should be careful not to send the wrong message to reduce intake of core grain foods.

A target number of wholegrain serves

Guideline 1 states ‘Eat a wide variety of nutritious foods including grain (cereal) foods, mostly wholegrain'. While the scientific evidence is growing on the benefits of wholegrain foods and high fibre grain foods, our Consumption Study in 2011 suggests that Australians are choosing wholegrains only once per day, which is less often than they were just two years ago. To help encourage Australians to eat more wholegrain foods and high fibre grain foods, Go Grains would like to see a recommended number of serves of wholegrains per day that reflects the evidence statements of 3 – 5 serves.

To align with the diet models which were used to develop the Guide to Healthy Eating, we suggest a recommendation that 2/3 of grain foods be wholegrain. For example for adults (19 – 50 years) ‘4 of the 6 serves of grain foods are wholegrain’.

Legumes

Go Grains believes that the benefits of legumes have been under-rated in the draft Dietary Guidelines. Legumes are not consumed regularly by many Australians despite their benefits in terms of nutritional quality, chronic disease risk reduction and environmental sustainability. To help encourage Australians to increase their intake of these unique foods we suggest that a weekly recommended intake be considered, based on scientific evidence. Studies indicate eating 2 – 4 serves of legumes per week are associated with reduced risk of heart disease, cardiovascular disease and breast cancer.

For these reasons Go Grains will be recommending that:

• the serve sizes of grain foods are kept the same as the AGTHE 98• the recommendation of mostly wholegrain include a target number of wholegrain serves per day (eg: 4 of the 6 serves are wholegrain)• a recommendation to eat legumes at least 3 times a week is added

We will be commenting on these draft Guidelines and we urge you to do so as well. To review the draft documents and make a submission visit the dedicated website before February 29th http://www.eatforhealth.gov.au/.